Defrosting refrigeration system



Oct. 13, 1931. v. P. WARREN DEFROSTING REFRI(TrERATIONv SYSTEM Filed April 18. 1930 2 Sheets-Sheet 1 gwowtoz Ill 312 1? Warren @mmv Oct. 13, 1931. v. P. WARREN DEFROSTING REFRIGERATION SYSTEM Filed April 18. 1930 2 Sheets-Sheet 2 314 06144201; 111')" z! B Warren Patented Oct. 13, 12931 UNITED STATES VIRGIL P. WARREN, OF ATLANTA, GEORGIA DEFROSTING REFRIGERATION SYSTEM Application filed April 18,

This invention relates to mechanical refrigeration and particularly, although not exclusively, to show case refrigeratlon.

The general object of the invention provides means and a method for defrosting the refrigerating coils and for preventing the water which eventuates from the defrost ng, collecting and freezing at any undesired point in the refrigeration apparatus.

A more specific object of the lnventlon 1s the provision of a refrigerating system of the Carnot cycle type modified by means which can be periodically manipulated to cause the circulation of the hot compressed gaseous refrigerant through the refrigerating coils and through other conduits disposed in advantageous positions to prevent the freezing of the drainage from the defrosting operation.

A further object of the invention is to provide a valve controlled conduit connected into the refrigeration circulation system in such a manner that the circulation of refrigerating medium may be made to by-pass the condenser, said conduit extending from the compression end of the compressor, first into heat exchanging relationship with a drainage conduit arranged below the coil, and then communicating with the coil whereby the hot compressed. refrigerating medium will be circulated, first in proximity to the drainage conduit and then through the coil, maintaining the drainage conduit suificiently warm during the defrosting period to prevent clogging of the drain by freezing of the moisture defrosted from the coil and which would result in an over-flow of said moisture into the chamber of the show case.

Another object of the invention is the construction of the pan or enclosure which houses the refrigerating coils and defines the circulation of air about said coils and within the show case, particularly in its cooperative relation to the defrosting system whereby the metal of the pan at the lower-most part and adjacent the drain, is madeto contact intimately with the defrosting conduit.

Other objects of the invention will appear as the following description of a preferred embodiment thereof proceeds.

1930. Serial' No. 445,371.

Before referring to the drawings, it ma be said that with the advent of the quic I freezing process of meats, fish, poultry and fruits, a problem arises of furnishing show cases capable of maintaining a very low temperature, for example, from fifteen to twenty degrees Fahrenheit. At this low temperature, the coils will collect frost and ice very rapidly, and consequently, must be defrosted,

since a heavily frosted coil is quite inefiicient in its .heat exchanging capacity, the encrusted ice acting as a heat insulation.

The usual procedure in defrosting a coil is to cut off the refrigeration, open up the show case, and allow the atmospheric temperature to heat the coil to a temperature above freezing in order for the ice to melt.

.This generally requires several hours, in

which time the contents of the case become heated up, a condition which wouldbe inimical to the proper preservation of meats frozen by the new quick-freeze process. Consequently, one of the conditions upon which the salability of quick-frozen products depends is that the temperature of the product shall never rise above the freezing point. The present invention overcomes this difficulty by providing an entirely new system of defrosting which does not require that the show case be opened up at all and which takes but a few minutes to accomplish as compared with hours in the known method.

In the drawings which illustrate the present invention and in which the same charac- Figure 6 is a section taken along the line 6-6 of Figure 2.

Referring now in detail to the several fig- 'ures, and adverting to Figure 1, a Carnot c cle refrigeration system is shownin which tlie compressor 1 delivers the hot compressed gaseous refrigerant through a conduit 2 to a condenser 3 in which it is liquefied and stored in the reservoir 4, the cold liquid refrigerant filling the conduit 5 up to the expansion valve 6 beyond which, the liquefied refrigerant is permitted to expand into the. coil 7, the expansion being attended by absorption of heat from the air surrounding the coil 7, the latter performing its refrigerating function in usual and known manner.

Since the present invention is particularly adapted for show case use, the several convolutions of the refrigeratingcoil 7 are shown in Figure 2 suspended from the top wall of a show case. 'The refrigerating unit herein illustrated is that described and claimedin the co-pending application of Lester U. Larkin, Serial No. 422,364, which is known as a .dry system.

In Figure 1,'the several convolutions of the coil 7 are shown as passing throu h a plurality of heat dissipating plates or fins 8. The spent, expanded and somewhat heated gaseous refrigerant returns from the coil 7 by way of the conduit 9, back to the suction side of the compressor where it is again compressed, the refrigerating cycle being thus repeated.

Although the invention is particularly adapted to a dry coil system of refrigeration, there is nothing inherent in its defrosting principle that bars it from application to any system in which a supply of heated gaseous refrigerant is available as the defrosting medium.

The concept of the present invention, broadly stated is, for the purpose of defrosting, to by-pass the heated compressed gaseous refrigerant in the conduit 2 around the condenser so that it will not be cooled and liquefied and to admit it in heated state to the refrigerating coil substituting the same temporarily for the cold expanding refregerant. In order to carry out the principle embraced in this concept, a air of three-way valves 10 and 11 are provided, one being intercalated in the hotcompressed gas conduit 2, between the compressor and condenser, and the other being interposed in the refrigerating unit between the expansion valve 6 and the coil 7. These valves may be of similar construction, and there is nothing inherently new in their construction, per se. The cross-section shown in Figure 3 is that of either of the three-way valves. For example, valve 10 shows that in one position of the valve the conduit 2 is open to the confpass pipe 12. The valve 11 in one denser, while in another osition of the'valve, the conduit 2 is occluded with respect to the condenser, but open with regard to the byosition opens the expansion valve to the coil while in another position the expansion valve is closed, the coil 7 being 0 en to the by-pass Assuming that the re rigeratingcyele has operated for a number of hours and that a layer of frost has condensed upon the coil 7, the operator merely turns the valves 10' and 11 so that each is in position indicated in Figure 3, closing the system to the condenser and expansion valve and opening it to the b pass. The compressor then pumps t e heated gaseous refrigerant through said bypass and directly into the coil 7, heating it and condensing. the frost inerustation. At the temperature of the compressed gaseous refrigerant this defrosting takes but little time, ordinarily from five to fifteen minutes according to the thickness of the frost layer. There is not time for any appreciable rise in the temperature of the atmosphere within the show case.

In testing out the invention it has been found that after running the hot gaseous refrigerant through the coil 7 in defrostin the coil, the atmosphere in the top of the s ow case did not rise more than five degrees, while in the bottom of the show case no rise was perceptible. The maintenance of the low temperature in the show case while the defrosting is going on is due to the fact that the defrosting takes place from the inside, and that while any frost at all remains on the coil 7, it acts as a heat insulation preventing the heat from the defrosting fluid being dissipated in the show case until the last ,vestige of frost is gone. As the three-way valves are then turned to restore the refrigcrating operation, this recommences immediately and a little more vigorously than normally, since the expansion valve has been heated due to-its proximity to the course of the defrosting fluid so that expansion takes place at the start more vigorously.

Referring now to Figure 2, it will be noted that the coil 7 is suspended from the top of the show case in any suitable manner as for instance, between screw eyes 13 through the eyes of which is passed a rod 14 extending beneath a layer of the coils and between certain of the fins 8. There may be one of these suspending rods at each end of the coil or a plurality of the same, depending of course upon the length of the coil within the show case. The coil is preferably housed within a pan 15. Said pan is preferably of laminated constructionas-shown having inner and outer walls 37 and 38 of metal and a sheet 39 of asbestos or other insulation material between, the idea being to conserve ,the refrigeratin temperature within said pan and about t e convolutions of said coil courses through the show case and into and I out of contact with the refrigerating unit.

In order to determine a uniform circulation of refrigerated air in all parts of the show case, the pan 15 is constructed to operate according to the so called two-cycle principle. That is to say, two similar air eddies are maintained, one at the front and one at the back of the show case. T'histype of air circulation is produced by the pan having an elongated slot or opening 16 at its lower-most portion, in the middle, said slot being roofed by-a bridge 36, the same being also of laminated construction having inner and outer metal layers and an intermediate heat insulating layer, and being spaced at its sides from the pan formingcold air ports 17 and 18.

. It will be noted that the pan does not ex tendclear to the top Wall 8' of the show case but terminates at a distance below it, as shown at 19 and 20, the space above, between said pan and show case affording an inlet at each side, for the current of relative- 1y warm air to flow in to the refrigerating unit. The fins 8 are arranged cross-wise as shown so as to oppose minimum obstruction to the entrance of the air. The circulation of air is as follows:

Relatively warm air rises along the front and back Walls of the show case, enters the inlets at the sides of the pan 15 flows over the convolutions of the refrigerating coil 7 descends by gravity within the pan and issues through the ports 17 and 18, flowing through the slot 16 down upon the produots which are to be maintained below freezing point.

The pan as shown in the illustration has u turned ends 21 and 22 constituting sides of the slot 16. and forming gutters 23 from which lead drain pipes 24 which extend outside of the show case.

the defrosting freezes in the gutters 18 and in the drain pipes 24 stopping up the latter and preventing their proper functioning so that there is an overflow of the water on to the frozen products. I

The present invention obviates this difficulty by extending the by-pass conduit 12 a which by-passes the condenser and expansion valve in the form of a loop or coil 25 extending along the sides of the slot 16 and in heat exchanging relation thereto. In order to extend the conduction of heat from the coil 25 as far as possible with regard to the adjacent portions of the pan 15, the coil 25 is laid in the angles formed by the up-turned ends 21'and 22, in intimate contact with the inner metal surfaces thereof, and separate metallic channel members placed over said coils preferably in intimate contact therewith at one side and top, the other sides of said channel members being in contact with the outer metallic walls of the pan 15, heat from said coil thus being conducted through the inner and outer walls of the pan to the drain pipes 24. It thus becomes impossible for ice to accumulate in the gutters 23 and drain pipes 24, since the regions of these parts are heated to at least the same extent as the convolutions of the coil 7 It is to be understood that in the defrosting system 'of the present invention, no liquid refrigerant traverses the coil 25, except that which condenses insaid coil as only the heated compressed gases make this circuit and any gas that is condensed in the coil 25 or coil 7 is drawn back through the suction line and compressed and reheated by the action of the compressor in the regular way and again sent around the continuous circuit in the form of hot gas.

This continuous operation is carried on automatically through the operation of the compressor and requires positively no attention other than the opening of the three-Way valves to start the defrosting cycle and closing them to restore to the system its refrigerant cycle.

While I have in the above description disclosed what I believe to be a preferred and practical form of my invention, it is to be understood that changes in the detailed construction or arrangement of the several parts can be contemplated without transcending the scope of theinvention as claimed.

What I claim is:

1 Defrosting refrigeration circulation system including a compressor and a refrigerating coil, a pan underlying said coil, a drain from said pan, and parallel branches betweenthe pressure side of said compressor and said coil, one of said branches including a condenser, and the other of said branches having a portion arranged adjacent the drain of said pan and in heat exchanglng relation thereto, and means for selectively determining the path of flow of said refrigerant throu h one or the other of said branches.

2. fiefrosting refrigeration circulation system including a compressor and a suspended refrigerating coil, a pan underlying said coil, a drain from said pan, arallel branches between the pressure side of said compressor and said coil, one including a condenser and the other being arranged adjacent said drain and in heat exchanging relation thereto, and means for selectively determining the path of flow of said refrigerant through one or the other of said branches.

3. Defrosting refrigeration circulation syssaid vent, parallel branch conduitsbetween the pressureside of said compressor and said .10

coil, one including a condenser and the other 7 having aportion disposed adjacent said drainage means and in heat exchangingrelation thereto, and means for selectively determining the path of flow of said refrigerant through one or the other of said branches.

4. Defrostingrefrigeration circulation sys tem including a compressor and a refrigerating coil, a showcase in which said refrigerating'coil is suspended, a pan underlying said coil having a cold air vent at the bottom and an air inlet adjacent the top determining circulation of air through said show case,

drainage means for said pan adjacent said vent, and parallel branches between the pressure side of said compressor and said coil, one including a condenser and the other having a portion arranged adjacent said vent and in heat exchanging relation thereto, and means for selectively determining the path of flow of said refrigerant through oneor the other of said branches.

5. Defrosting refrigeration circulation system including a compressor and a refrigerating coil, a show case in which said refrigerating coil is suspended, a pan underlying said coil having a cold air vent at the bottom and an air inlet adjacent the top on each side, determining circulating currents of air within said show case, drainage means adjacent said vent, parallel branches between the pressure side of saidcompressor and said coil, one including a condenser and the other having a portion arranged adjacent said drainage means and in heat exchanging relation thereto, and means for selectively determin ing the path of flow of said refrigerant through one or the other of said branches.

6. Air circulating means for show case refrigerating coils, the latter forming part of a refrigeration system having a compressor and condenser, saidmeans comprising a pan underlying the coil within the show case, said pan having a cold air vent in the bottom and air inlets at the sides above the level of the cold air vent, determining air circulation anemic the metal surface of said'pan adjaeentsaid draina e means. a f

7. Air circulating means for how case refrigerating coils, the latter forming part of a refrigeration system having 7 a compressor and condenser, said air circulati means comprising a pan underlying said 001 within the show case having inclined bottom walls terminating in up-turned s a'ced flanges, defining on the one hand a co d air vent and on the other handvalleys, draina e means communicating with said valleys, said pan having air inlets at the sides above the level" of said cold air vent determining air 'circulationcurrents within said show case and about said coil, said pan being of laminated construction with metal surface layers and an intermediate layer of insulating materlal, and a defrosting conduit positioned in' said valleys-in intimate contact with the metal surfaces of said pan, said conduit being adapted to communicate with'the compression side of a compressor between the said compressor and condenser.

8. Air circulation means for show case refrigerating coils as claimed in claim 7 including a bridge between said coil and said cold air vent spaced from the latter to form cold air ports on either side, said bridge being of lam nated construction including an intermediate layer of heat insulating material.

9. The method of defrosting the refrigerating coil of a refrigeration system of the Carnot typeT'and at the same time preventin ice formation in a' drain beneath said coil comprising: by-passing periodically at 'intervals according to frost conditions-on the coil surface, hot gaseous refrigerant direct to said coil and in heat exchangin relation to the dram WlthOllt passing it t rough the condenser. 7

In testimony-whereof ll afix my si 5 ature.

\ VERGIL P. WARl'fEN.

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